What exactly is the gas limit per Block?

I just read about EIP 1559 and im wondering what exactly the gas limit per block means.

Why do we have a limit of 12,5m per Block on the Ethereum Blockchain?

Is the raise to max 25m per Block just for the equilibrium mechanics so they can adjust the base fee?

Means 25m Gas, that if im willing to pay (basefee+tip=25m gwei) i get my very own block for my transaction?

I think im missing something, because i dont really get what gas is and how much is used per transaction etc.

If its that easy to raise gaslimit and get more tps, why dont we have 100m blocks?

Why, if the max gas limit is really high it can happen you mine an empty block? what is an empty block?

Any help is really appreciated!